Direct numerical simulation of turbulent mixing in grid-generated turbulence

Kouji Nagata, Hiroki Suzuki, Yasuhiko Sakai, Toshiyuki Hayase, Takashi Kubo

Research output: Contribution to journalConference articlepeer-review

41 Citations (Scopus)


Turbulent mixing of passive scalar (heat) in grid-generated turbulence (GGT) is simulated by means of direct numerical simulation (DNS). A turbulence-generating grid, on which the velocity components are set to zero, is located downstream of the channel entrance, and it is numerically constructed on the staggered mesh arrangement using the immersed boundary method. The grid types constructed are: (a) square-mesh biplane grid, (b) square-mesh single-plane grid, (c) composite grid consisting of parallel square-bars and (d) fractal grid. Two fluids with different temperatures are provided separately in the upper and lower streams upstream of the turbulence-generating grids, generating the thermal mixing layer behind the grids. For the grid (a), simulations for two different Prandtl numbers of 0.71 and 7.1, corresponding to air and water flows, are conducted to investigate the effect of the Prandtl number. The results show that the typical grid turbulence and shearless mixing layer are generated downstream of the grids. The results of the scalar field show that a typical thermal mixing layer is generated as well, and the effects of the Prandtl numbers on turbulent heat transfer are observed.

Original languageEnglish
Article number014054
JournalPhysica Scripta T
Publication statusPublished - 2008
Externally publishedYes
EventInternational Conference 'Turbulent Mixing and Beyond' - Trieste, Italy
Duration: Aug 18 2007Aug 26 2007

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Mathematical Physics
  • Condensed Matter Physics


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